Plastic carriers for the so-called "six-pack" have been on super market shelves for many years. They are usually made by die cutting from extruded sheet. Slip additives and antiblock agents are included in the pre-extrusion can carrier composition to impart the surface properties which enhance die cutting and the application of the carrier to cans. Historically, primary fatty acid amides such as erucamide and oleamide have served as slip additives and silica has performed the function of antiblock agent. However systems using these components have had drawbacks, e.g. accelerated dulling of punch tooling and grinder blades caused by the very hard silica; plateout of the amide onto the punch press feed rollers and dies, adversely affecting the dimensions of the carriers punched; and failing to allow "facing" of the cans in the carrier. "Facing" is the purposeful twisting of cans in a six-pack to align their logos for the sake of appearance on store shelves. Soft drinks sweetened with cane syrup can have sufficient spillage residue to adhere the cans to carriers applied later. Any subsequent effort to twist those cans for the purpose of "facing" can cause the carrier to rupture rather than permitting the can to turn easily unless a slip additive is present. These problems have been solved by using a secondary amide such as erucyl erucamide as a slip additive and talc coated with zinc stearate as an antiblock agent.
The art is still seeking can carrier compositions with improved environmental stress crack resistance to resist the rupture and subsequent can fall out caused by cracks in the carriers that occur when stressed carriers are subjected to wetting media, e.g., detergent solution, especially in warm environments. As will be seen hereinafter, however, the provision of such compositions leads to associated problems, which must be solved.